Examples of heat decoloration type reversible thermochromic materials heretofore in use include a reversible thermochromic composition comprising a homogeneous compatibilized material which comprises the following three components: (a) an electron-donating chromic organic compound, (b) an electron-accepting compound, and (c) a reaction medium which determines the temperatures at which color reactions between the components (a) and (b) occur. This composition is extensively used in toys, printed matters, etc. (see, for example, patent document 1 to 3).
However, these reversible thermochromic materials each have a single thermochromic function, i.e., they are decolored by heating in a colored state and colored by cooling in a decolored state. Consequently, the visual effect of thermochromism brought about by heating or cooling has unavoidably been monotonous in some degree.
The applicant hence further proposed a reversible thermochromic display article employing a combination of a heat coloration image and a heat decoloration image (see, for example, patent document 4).
This reversible thermochromic display article can show a variety of thermochromic behaviors depending on combinations of a heat coloration image and a heat decoloration image, and has a remarkable visual effect rich in the niceties of color changes and in the surprising and magical nature thereof.
This reversible thermochromic display article is constituted of a heat coloration type reversible thermochromic material and a heat decoloration type reversible thermochromic material, and is characterized in that the heat coloration type reversible thermochromic material contains an alkoxyphenol compound and/or a hydroxybenozic ester compound as an electron-accepting compound, component (b)′.
[Patent Document 1]
U.S. Pat. No. 4,028,118
[Patent Document 2]
U.S. Pat. No. 4,732,810
[Patent Document 3]
U.S. Pat. No. 4,720,301
[Patent Document 4]
JP-A-2000-194295